A battery module has been mounted on an electric vehicle or the like. For example, a battery module is disclosed in Japanese Patent No. 5405102 which is formed by a plurality of cells stacked in a front-rear direction and includes a cell stack body having a front surface, a rear surface, a left surface, a right surface, an upper surface, and a lower surface, a pair of end plates disposed on the front surface and the rear surface of the cell stack body, and a fastening frame for connecting the pair of end plates.
In this type of battery module, a load in a cell stacking direction of the battery module (hereinafter, appropriately referred to as a cell thickness constraint reaction force) occurs due to expansion of the cell caused by temperature change and aging deterioration. In recent years, since more active material is packed in the cell in accordance with the high capacity and the high energy density of the cell, the cell thickness constraint reaction force tends to increase.
As disclosed in Japanese Patent No. 5405102, however, when the battery module includes side frames (metal bands) disposed on the right surface and the left surface of the cell stack body and the side frames respectively include side frame bodies and a front turn-around portion and a rear turn-around portion that turn around the front surface and the rear surface of the cell stack body (end plate) from the side frame body, since a load in a cell stacking direction due to expansion of the cell intensively acts on the front turn-around portion and the rear turn-around portion of the side frame, the front turn-around portion and the rear turn-around portion may be deformed in an opening direction, and movement of the end plates or dimensional variation of the battery module may occur.